Doping of organic materials with electron acceptors to increase the conductivity of hole conductor layers has been demonstrated many times in the literature (see, for example, G. He, 0. Schneider, D. Qin, X. Zhou, M. Pfeiffer, and K. Leo, Journal of Applied Physics, 95, 5773-5777 (2004)).
Doping can increase the conductivity of the material by orders of magnitude.
There is a fundamental need for further dopants, particularly inexpensive dopants, for hole transport layers.